Compilare: In file included from user.c:8:0: /usr/include/i386-linux-gnu/sys/ipc.h:25:3: warning: #warning "Files using this header must be compiled with _SVID_SOURCE or _XOPEN_SOURCE" [-Wcpp] # warning "Files using this header must be compiled with _SVID_SOURCE or _XOPEN_SOURCE" ^ user.c: In function ‘main’: user.c:55:7: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, &size, 1); ^ user.c:56:7: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, x, sizeof(char)*size); ^ user.c:57:6: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] read(fd1, &size_field, 1); ^ user.c:58:6: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] read(fd1, &the_string, size_field); ^ user.c:69:9: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, &length, 1); ^ user.c:70:9: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, "PING", size_field); ^ user.c:71:9: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, &length, 1); ^ user.c:72:9: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, "PONG", size_field); ^ user.c:73:9: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, &variant, sizeof(int)); ^ user.c:79:8: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] read(fd1, &number, sizeof(long)); ^ user.c:85:10: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, &size_field, 1); ^ user.c:86:10: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, "CREATE_SHM", size_field); ^ user.c:88:10: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, &size_field, 1); ^ user.c:89:10: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, "ERROR", size_field); ^ user.c:99:10: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(fd, &size_field, 1); ^